Cutting devices

Abstract

A cutting device may include a friction reducing device arranged in an operational force transmission path between an operation member and a fixing device that can fix a circular cutter to a rotational shaft of a cutting unit.

What is claimed is: 
     
       1. A cutting device comprising:
 a cutting unit having a rotational shaft; 
 a fixing device configured to fixedly attach a circular cutter to the rotational shaft; and 
 an operation device coupled to the fixing device; 
 wherein the operation device comprises: 
 an operation member configured to apply an operational force to the fixing device for fixation of the circular cutter to the rotational shaft and for releasing fixation of the circular cutter to the rotational shaft; and 
 a friction reducing device arranged in an operational force transmission path between the operation member and the fixing device and configured to reduce a frictional force produced between the operation member and the fixing device when the operation member applies the operational force to the fixing device, wherein: 
 the operation member comprises an operation shaft and an operation knob, 
 the operation shaft is coupled to the rotational shaft, so that the operation shaft is coaxially rotatable relative to the rotational shaft and movable relative to the rotational shaft in an axial direction of the rotational shaft, 
 the operation knob has an outer portion defining an outer peripheral surface and an inner portion including an engaging portion engaging the operation shaft in the rotational direction, 
 the outer portion and the inner portion are connected to each other and extend coaxial with each other in the axial direction, 
 the friction reducing device comprises a bearing coaxially fitted on the operation shaft, 
 an engaging device is disposed between an outer peripheral surface of the operation shaft and an inner peripheral surface of the inner portion of the operation knob and is configured to inhibit movement of the inner portion of the operation knob away from the rotational shaft in a first direction along the axial direction, 
 the bearing contacts a part of an outer peripheral portion of the operation shaft in the axial direction, 
 the inner portion of the operation knob has an end portion in a second direction, which is along the axial direction and opposite to the first direction, and 
 the end portion of the inner portion of the operation knob is directly opposed to and abuts the bearing in the axial direction when the operation knob is moved in the axial direction during rotation of the operation knob. 
 
     
     
       2. The cutting device according to  claim 1 , wherein:
 the operation shaft is movable relative to the rotational shaft in the axial direction toward and away from the fixing device as the operation knob rotates. 
 
     
     
       3. The cutting device according to  claim 2 , wherein the bearing is a rolling bearing arranged between the operation member and the fixing device in the axial direction. 
     
     
       4. The cutting device according to  claim 3 , wherein the rolling bearing is a thrust needle bearing. 
     
     
       5. The cutting device according to  claim 2 , wherein:
 the operation device further comprises a thread engaging member threadably engaged with the rotational shaft, so that the thread engaging member moves in the axial direction as the thread engaging member rotates about an axis of the rotational shaft; 
 the operation member is coupled to the thread engaging member, so that the operation member moves together with the thread engaging member in the axial direction as the operation member rotates; and 
 the operation member is configured to be manually rotatable. 
 
     
     
       6. The cutting device according to  claim 5 , wherein:
 the operation device further comprises a pressure applying member rotatable relative to the operation member about the axis of the rotational shaft and is axially opposed to the fixing device; and 
 the friction reducing device is arranged between the operation member and the pressure applying member. 
 
     
     
       7. The cutting device according to  claim 5 , further comprising:
 an operational force control device coupled to the operation device and operable to shift an axial position of the operation member to increase or decrease the operational force applied to the fixing device. 
 
     
     
       8. The cutting device according to  claim 7 , wherein:
 the operation member is movable relative to the thread engaging member between a first position and a second position spaced from the first position in the axial direction away from the fixing device; 
 the operational force control device comprises: 
 a spring configured to apply an urging force to the operation member in the axial direction toward the first position so as to retain the operation member at the first position; and 
 a control member operable to shift the operation member from the first position to the second position against an urging force of the spring. 
 
     
     
       9. The cutting device according to  claim 6 , further comprising:
 the operation device further includes a wedge mechanism including a wedge member movable between a lock position and a lock releasing position; 
 wherein the wedge member engages the pressure applying member so as to press the pressure applying member against the fixing device when the wedge member is positioned at the lock position; 
 the friction reducing device comprises a wedge control device operable to move the wedge member from the lock position to the lock releasing position in response to the rotation of the operation member in a direction for releasing fixation of the fixing device. 
 
     
     
       10. The cutting device according to  claim 2 , wherein the operation member is configured to be manually rotatable and is also configured to be rotatable by using a wrench. 
     
     
       11. The cutting device according to  claim 10 , wherein:
 the operation knob is coupled to the operation shaft so as to be rotatable together with the operation shaft; and 
 the operation knob has an outer peripheral portion configured to be engageable with fingers of a user. 
 
     
     
       12. The cutting device according to  claim 11 , wherein:
 the operation shaft has an axial end on a side away from the rotational shaft; and 
 an operation hole capable of engaging the wrench is formed in the axial end of the operation shaft. 
 
     
     
       13. The cutting device according to  claim 11 , wherein the friction reducing device is disposed within a radial space defined between the outer peripheral portion of the operation knob and the operation shaft. 
     
     
       14. The cutting device according to  claim 13 , wherein:
 the operation device further comprises a pressing member that is coaxially rotatable fitted on the operation shaft; and 
 the bearing is axially interposed between the operation knob and the pressing member. 
 
     
     
       15. The cutting device according to  claim 1 , wherein:
 the operation device further comprises a pressing member; 
 the bearing is interposed between the inner portion of the operation knob and the pressing member in the axial direction; and 
 a movement prevention device is provided between the operation shaft and the pressing member and is configured to prevent movement of the pressing member in the second direction, so that the movement in the second direction of the bearing and the inner portion of the operation knob is prevented by the movement prevention device via the pressing member. 
 
     
     
       16. The cutting device according to  claim 1 , wherein:
 the operation shaft includes a first shaft portion on a side of the first direction, a second shaft portion on a side of the second direction, and an intermediate shaft portion between the first shaft portion and the second shaft portion; 
 an outer diameter of the first shaft portion is larger than an outer diameter of the intermediate shaft portion, so that a first stepped portion is formed between the first shaft portion and the intermediate shaft portion, the first stepped portion having a first surface extending substantially in a radial direction and oriented in the second direction; 
 the outer diameter of the intermediate shaft portion is larger than an outer diameter of the second shaft portion, so that a second stepped portion is formed between the intermediate shaft portion and the second shaft portion, the second stepped portion having a second surface extending substantially in a radial direction and oriented in the second direction; 
 the inner portion of the operation knob includes a first inner portion and a second inner portion respectively fitted on the first shaft portion and the intermediate shaft portion; 
 the engaging device comprises the first stepped portion of the operation shaft, so that the second inner portion is prevented from moving in the first direction by the first stepped portion; 
 the bearing is in contact with the second surface of the second stepped portion, so that the bearing is prevented from moving in the first direction; and 
 the second inner portion of the operation knob has an end portion in the second direction, the end portion has an end surface directly facing the bearing in the axial direction and positioned substantially within a same plane as the second surface of the second stepped portion of the operation shaft. 
 
     
     
       17. The cutting device according to  claim 1 , wherein the operation knob further comprises a connecting portion extending in a radial direction and connecting an end portion in the first direction of the outer portion and an end portion in the first direction of the inner portion. 
     
     
       18. The cutting device according to  claim 1 , wherein the inner portion of the operation knob includes an outer peripheral surface facing the outer portion, and a diameter of the outer peripheral surface is substantially equal to an outer diameter of the bearing. 
     
     
       19. A cutting device comprising:
 a cutting unit having a rotational shaft; 
 a fixing device configured to fixedly attach a circular cutter to the rotational shaft; and 
 an operation device coupled to the fixing device; 
 wherein the operation device comprises: 
 an operation member configured to apply an operational force to the fixing device for fixation of the circular cutter to the rotational shaft and for releasing fixation of the circular cutter to the rotational shaft; and 
 a friction reducing device arranged in an operational force transmission path between the operation member and the fixing device and configured to reduce a frictional force produced between the operation member and the fixing device when the operation member applies the operational force to the fixing device, wherein: 
 the operation member comprises an operation shaft and an operation knob, 
 the operation shaft is coupled to the rotational shaft, so that the operation shaft is coaxially rotatable relative to the rotational shaft and movable relative to the rotational shaft in an axial direction of the rotational shaft, 
 the operation knob has an outer portion defining an outer peripheral surface and an inner portion including an engaging portion engaging the operation shaft in the rotational direction, 
 the outer portion and the inner portion are connected to each other and extend coaxial with each other in the axial direction, 
 the friction reducing device comprises a bearing coaxially fitted on the operation shaft, 
 an engaging device is disposed between an outer peripheral surface of the operation shaft and an inner peripheral surface of the inner portion of the operation knob and is configured to inhibit movement of the inner portion of the operation knob away from the rotational shaft in a first direction along the axial direction, 
 the bearing contacts a part of an outer peripheral portion of the operation shaft in the axial direction, 
 the inner portion of the operation knob has an end portion in a second direction, which is along the axial direction and opposite to the first direction, 
 the end portion of the inner portion of the operation knob is directly opposed to the bearing in the axial direction, 
 the operation device further comprises a pressing member that is coaxially rotatable fitted on the operation shaft, and 
 the bearing is axially interposed between the operation knob and the pressing member. 
 
     
     
       20. A cutting device comprising:
 a cutting unit having a rotational shaft; 
 a fixing device configured to fixedly attach a circular cutter to the rotational shaft; and 
 an operation device coupled to the fixing device; 
 wherein the operation device comprises: 
 an operation member configured to apply an operational force to the fixing device for fixation of the circular cutter to the rotational shaft and for releasing fixation of the circular cutter to the rotational shaft; and 
 a friction reducing device arranged in an operational force transmission path between the operation member and the fixing device and configured to reduce a frictional force produced between the operation member and the fixing device when the operation member applies the operational force to the fixing device, wherein: 
 the operation member comprises an operation shaft and an operation knob, 
 the operation shaft is coupled to the rotational shaft, so that the operation shaft is coaxially rotatable relative to the rotational shaft and movable relative to the rotational shaft in an axial direction of the rotational shaft, 
 the operation knob has an outer portion defining an outer peripheral surface and an inner portion including an engaging portion engaging the operation shaft in the rotational direction, 
 the outer portion and the inner portion are connected to each other and extend coaxial with each other in the axial direction, 
 the friction reducing device comprises a bearing coaxially fitted on the operation shaft, 
 an engaging device is disposed between an outer peripheral surface of the operation shaft and an inner peripheral surface of the inner portion of the operation knob and is configured to inhibit movement of the inner portion of the operation knob away from the rotational shaft in a first direction along the axial direction, 
 the bearing contacts a part of an outer peripheral portion of the operation shaft in the axial direction, 
 the inner portion of the operation knob has an end portion in a second direction, which is along the axial direction and opposite to the first direction, and 
 the end portion of the inner portion of the operation knob is directly opposed to and abutting the bearing in the axial direction.